Industry Questions - 20200827 Moose Creek Dam Mod TRACK CHANGES.docx

Moose Creek Dam Modification Chena River Lakes Flood Control Project The Moose Creek Dam modification project will construct a mix-in-place barrier wall in the embankment of Moose Creek Dam at the Chena River Lakes Flood Control Project. This will consist of constructing 4.5 miles of barrier wall 56 61 to 66.567 feet below the crest of the dam embankment with Portland Cement and Bentonite. The barrier wall is expected to be between 18 and 30a minimum of 24 inches wide and have an a 10 day rolling average unconfined compressive strength of 200 psi at 28 days and approach 500 psi in the long termnothing below 150 psi. Sheet pile will be driven around the low point drain and jet grouting at the control works to have a continuous wall through penetrations in the embankment. The intent of the barrier wall is to sever a continuous fine grained sand / silty sand that is highly erodible under the embankment material. Allowable construction technology will consist of Cutter Soil Mix (CSM) or Trench Remixing and Deep Wall (TRD) methods to construct the mix in place wall. Clamshell/Hydromill or long stick excavator methods with use of a slurry trench will NOT be utilized for barrier wall construction. Foundation and embankment materials will not allow a Bentonite slurry trench. Loss of slurry could result in failure of the embankment into the trench during construction. Mix-in-place methods shall be utilized to mix the embankment and foundation materials with Bentonite and Portland Cement in order to construct a barrier wall. Any methods that utilize a bentonite slurry trench to support the embankment while excavation of barrier wall takes place will not be utilized at Moose Creek Dam. The potential loss of slurry could result in failure of the embankment into the excavation during construction due to the highly pervious foundation materials.

Questions for Sources Sought

Contracting Questions

1. Do you support or oppose a project labor agreement (PLA) factor as part of the solicitation requirements?

a. How could a PLA affect the cost of the project? Increase/decrease? How?

b. Could a PLA minimize risk to the Government on this project?

c. What is the time impact to the completion of the contract due to a PLA?

2. What do you see as small business opportunities to support this project?

a. What percentage of the project do you believe small businesses will be able to do?

Technical

1. Experience on USACE/far north projects?

2. Wall width min/max?

3. Wall depths min/man?

4. What method of Wall construction would you propose?

5. Starting and Stopping?

5.1. Does the machine need to be removed from the ground?

6. What method is used to tie into existing structures?

6.1. Is the structure damaged?

6.2. How close is the tie in to the structure?

6.3. Do you have experience tying in mix-in-place methods with jet grouting?

7. How easy is it to change depths?

8. Work platform requirements?

8.1. Degrade crest?

8.2. Other site prep?

8.3. Does work Platform need to have access around wall equipment? (Passing room for trucks)

8.4. After seeing the site do you feel degrading the crest is needed?

9. Concerns with permafrost?

10. Concerns with foundation materials?

11. Does high water table effect placement?

12. Segregation concerns?

13. Does a certain type of mix work better with your machine than another? (Cement, Bentonite, etc.)

14. Ambient operating temperature?

15. What sort of QC has been performed for placement?

15.1. Data collection capability? (logging machine location, speed of advance, RPM, verticality, material take/flow rate, etc. for post-construction quality verification)

15.2. Does your company have GIS personnel on staff already or would a subcontractor be required?

15.3. Does your company have someone familiar with SQL databases or would a subcontractor be required?

16. Typical working platform required?

17. Mix design?

17.1. How would you conduct a mix design?

17.1.1. What method would you follow?

17.1.2. Do you agree with the results of the Golder Mix Design?

17.1.3. Does it accurately portray findings of mixes and quantities of materials?

17.2. Do you have a Laboratory that you would use for Mix Designs?

17.2.1. Why do you use this lab to perform the mix design?

17.3. What kind of mix factors do you look at for your mix design?

17.3.1. How is bentonite and cement factored in your mix design?

17.4. What have you seen for strength gain over time for a mix in place wall?

17.5. Thoughts on dry mixing and its application at Moose Creek Dam?

18. The existing drain must remain intact. What means and methods would you recommend to limit the potential loss of cementitious materials into the adjacent rock drain at the base of the embankment during installation of the barrier wall?

18.1. Do you have any additional thoughts or concerns?

18.2. How much smear does your equipment have in dense soils?

18.3. How much smear does your equipment have in loose soils?

19. Permafrost is expected to be encountered. What limitations might this known site condition impose on the ability to achieve a uniform mix, with the required mix performance for the various types of M.I.P. equipment?

20. The purpose of the barrier wall is specifically to prevent internal erosion of the foundation soils through horizontal flaws above a certain depth. What QC/QA procedures would you employ during construction to ensure the finished barrier wall will have adequate properties to achieve this "no-erosion" goal?

21. What kind of depth transitions can your equipment perform?

21.1. Is it easy to change depths?

21.2. How often would you recommend depth changes and at what interval?

22. How do you account for mass volume calculations when determining quantities for a mix-in-place wall?

23. How do you handle water content below water table and above water table?

24. What is the lowest psi you would recommend for construction of this wall?

24.1. What would you expect the final psi to be for that recommendation?

25. Cobbles in the foundation were encountered during recent drilling operations. How would this affect your production and construction of the wall?

26. If placement of the wall was rejected what means and methods would you use to repair deficiency/replace?

26.1. Is there a time limit on how long after the wall is placed that the wall can be repaired/replaced?

27. Would you recommend any other construction technology for placement of the barrier wall? Note: A slurry that could seep into the gravel drain or highly permeable foundation material would not be permitted since loss of slurry would result in embankment not being supported.

28. Does the proposed project as described limit or exclude you from potentially bidding on the project?

28.1. If so how?

29. Do you anticipate using the Railroad tracks to offload material for the project?

30. Does the contractor have any concerns with the proposed laydown/staging area or borrow sources?

31. How many access ramps does the contractor anticipate needing?

31.1. Where would those access ramps be best placed?

32. Please discuss the use of jet grouting to tie the mix-in-place barrier wall into the existing concrete monolith at the Control Works, specifically address the existing 5V:1H sloped face of the concrete and working around the close edge of the retaining wall footing where it is closer than 8' from the Construction Base Line (centerline) of the dam.

33. Do you see a possibility of using jet grouting in lieu of sheet piles at the Low Point Drain to provide a complete barrier wall that extends below the base of the Low Point Drain's concrete culverts?

Wastage

34. At MCD, we'll be going from finer grained (embankment) into coarser materials (foundation) so waste generation will vary with depth. Would it be possible to adjust slurry addition (and waste) by depth by varying rotation and insertion rates?

35. What waste factor would you typically expect?

36. Do you have suggestions for other means of Rre-use of waste material?

37. Based on concern for waste generation and considering the embankment and foundation at MCD, what M-I-P method would you use and why?

38. How much migration (laterally) into the formation is expected with your construction technology based on soils?

39. How much waste comes to the surface?

40. What waste factor would you use for different construction technology from your experience? (Muli-auger, CSM, TRD, others)

Crew Data

41. Typical crew composition? (equipment/labor loadouts)

42. Production rates? (SF wall/HR)

43. Typical Hours of Operation/Work Schedule?

44. Seasonal weather concerns? (extreme cold, precip, etc.)

45. Mob/demob to Fairbanks, AK, concerns?

46. Specialty crews required?

47. How long would the job take? (generally in working days)

47.1. Would you consider multiple concurrent crews/equipment?

47.2. Construction window/seasons?

47.3. Wintering over ideas?

47.4. Mothball/multi-mob/demobs?

47.5. Equipment availability/ competing projects?

Are there any other items for consideration?